Carrier sense multiple access (CSMA) with frequency division multiplexing for data transmission in wireless communication

Abstract

A first communication device and a method performed thereby are provided for communicating with at least a second communication device. The first and the second communication device are operable in a wireless communication network employing contention based access for radio resources comprising a plurality of frequency subcarriers, wherein at least the second communication device transmits a control sequence on at least one subcarrier of a predefined subcarrier pattern when transmitting data. The method comprises: demodulating the radio resources on at least a subset of subcarriers of the predefined subcarrier pattern; and determining whether the demodulated radio resources comprise the control sequence; that being the case: refraining from transmitting data to the second communication device; and otherwise: transmitting data to the second communication device.

The invention claimed is: 
     
       1. A method performed by a first communication device for communicating with a second communication device, the first and the second communication devices operable in a wireless communication network employing contention based access for radio resources comprising a plurality of frequency sub carriers, wherein, when transmitting data, the second communication device transmits a control sequence on at least one subcarrier of a predefined subcarrier pattern comprising a set of subcarriers occupying a frequency range starting from a starting subcarrier according to a subcarrier pattern that uniquely identifies the second communication device or its type, the subcarrier pattern indicating at least one subcarrier to be used or to be left unused, the method comprising:
 at the first communication device:
 demodulating the radio resources on at least a subset of the set of subcarriers of the predefined subcarrier pattern; 
 determining whether the demodulated radio resources comprise the control sequence, which is transmitted with the data at the same time by the second communication device, within the predefined subcarrier pattern that uniquely identifies the second communication device or its type, the subcarrier pattern indicating at least one subcarrier to be used or to be left unused; 
 responsive to determining that the demodulated radio resources comprise the control sequence, which indicates the second communication device is transmitting the data, within the predefined subcarrier pattern that uniquely identifies the second communication device or its type, refraining from transmitting data to the second communication device; and 
 responsive to determining that the demodulated radio resources do not comprise the control sequence, which indicates the second communication device is not transmitting the data, within the predefined subcarrier pattern that uniquely identifies the second communication device or its type, transmitting data to the second communication device, wherein transmitting data further comprises transmitting a control sequence on at least one subcarrier of a predefined subcarrier pattern comprising a set of subcarriers occupying a frequency range starting from a starting subcarrier according to a subcarrier pattern that uniquely identifies the first communication device or its type, the subcarrier pattern indicating at least one subcarrier to be used or to be left unused. 
 
 
     
     
       2. The method according to  claim 1 , wherein the starting subcarrier in the predefined subcarrier pattern of the second communication device is an odd numbered subcarrier. 
     
     
       3. The method according to  claim 1 , wherein the starting subcarrier in the predefined subcarrier pattern of the second communication device is an even numbered subcarrier. 
     
     
       4. The method according to  claim 1 , wherein the control sequence is an all “0” sequence, and all “1” sequence, or a sequence of arbitrary elements. 
     
     
       5. A first communication device for communicating with a second communication device, the first and the second communication devices operable in a wireless communication network employing contention based access for radio resources comprising a plurality of frequency subcarriers, wherein, when transmitting data, the second communication device transmits a control sequence on at least one subcarrier of a predefined subcarrier pattern comprising a set of subcarriers occupying a frequency range starting from a starting subcarrier according to a subcarrier pattern that uniquely identifies the second communication device or its type, the subcarrier pattern indicating at least one subcarrier to be used or to be left unused, the first communication device comprising:
 one or more processors; and 
 memory storing instructions executable by the one or more processors, whereby the first communication device is configured for:
 demodulating the radio resources on at least a subset of the set of subcarriers of the predefined subcarrier pattern; 
 determining whether the demodulated radio resources comprise the control sequence, which is transmitted with the data at the same time by the second communication device within the predefined subcarrier pattern that uniquely identifies the second communication device or its type, the subcarrier pattern indicating at least one subcarrier to be used or to be left unused; 
 responsive to determining that the demodulated radio resources comprise the control sequence, which indicates the second communication device is transmitting the data, within the predefined subcarrier pattern that uniquely identifies the second communication device or its type, refraining from transmitting data to the second communication device; and 
 responsive to determining that the demodulated radio resources do not comprise the control sequence, which indicates the second communication device is not transmitting the data, within the predefined subcarrier pattern that uniquely identifies the second communication device or its type, transmitting data to the second communication device, wherein, when transmitting data, the first communication device is further configured for transmitting a control sequence on at least one subcarrier of a predefined subcarrier pattern comprising a set of subcarriers occupying a frequency range starting from a starting subcarrier according to a subcarrier pattern that uniquely identifies the first communication device or its type, the subcarrier pattern indicating at least one subcarrier to be used or to be left unused. 
 
 
     
     
       6. The first communication device according to  claim 5 , wherein the starting subcarrier in the predefined subcarrier pattern of the second communication device is an odd numbered subcarrier. 
     
     
       7. The first communication device according to  claim 5 , wherein the starting subcarrier in the predefined subcarrier pattern of the second communication device is an even numbered subcarrier. 
     
     
       8. The first communication device according to  claim 5 , wherein the control sequence is an all “0” sequence, and all “1” sequence, or a sequence of arbitrary elements. 
     
     
       9. A non-transitory computer-readable medium comprising instructions executable by processing circuitry of a first communication device for communicating with a second communication device, the first and the second communication devices operable in a wireless communication network employing contention based access for radio resources comprising a plurality of frequency subcarriers, wherein, when transmitting data, the second communication device transmits a control sequence on at least one subcarrier of a predefined subcarrier pattern comprising a set of subcarriers occupying a frequency range starting from a starting subcarrier according to a subcarrier pattern that uniquely identifies the second communication device or its type, the subcarrier pattern indicating at least one subcarrier to be used or to be left unused, whereby the first communication device is operable to:
 demodulate the radio resources on at least a subset of the set of subcarriers of the predefined subcarrier pattern; 
 determine whether the demodulated radio resources comprise the control sequence, which is transmitted with the data at the same time by the second communication device within the predefined subcarrier pattern that uniquely identifies the second communication device or its type, the subcarrier pattern indicating at least one subcarrier to be used or to be left unused; 
 responsive to determining that the demodulated radio resources comprise the control sequence, which indicates the second communication device is transmitting the data, within the predefined subcarrier pattern that uniquely identifies the second communication device or its type, refrain from transmitting data to the second communication device; and 
 responsive to determining that the demodulated radio resources do not comprise the control sequence, which indicates the second communication device is not transmitting the data, within the predefined subcarrier pattern that uniquely identifies the second communication device or its type, transmit data to the second communication device, wherein, when transmitting data, the first communication device is further operable to transmit a control sequence on at least one subcarrier of a predefined subcarrier pattern comprising a set of subcarriers occupying a frequency range starting from a starting subcarrier according to a subcarrier pattern that uniquely identifies the first communication device or its type, the subcarrier pattern indicating at least one subcarrier to be used or to be left unused.